Study On Synthesis Techniques Of Porous HAP Dispersant For Suspension Polymerization

The consumption of Hydroxyapatite (HAP) dispersants for suspension polymerization is the greatest in the world among inorganic dispersants. It is widely used in suspension polymerization of polystyrene (PS), expandable polystyrene (EPS), ABS resin, polymethyl methacrylate(PMMA) and styrene-arcylonitrile (SAN). It also can be used in suspension polymerization of polyvinyl chloride (PVC). This sort of dispersant can make the viscosity of reaction system easily control, the resin not easily stick on the kettle and agitator, so it can prolong the period of cleaning kettle, and reduce the production costs and decrease the environmental pollution.At present, most of selling homeproduced HAP dispersants for suspension polymerization have large particle size and wide grain size distribution.Therefore they have low activity and dispersibility. When these HAP dispersants are used in polymerization of resins, they can make the quality of these resin products poor. Because the activity of HAP dispersant for suspension polymerization is proportional to its specific surface area, foreign investigators try to make HAP dispersant particles become superfine and make the particle size reach to nanometer level so as to increase its specific surface area and to improve its dispersion activity. Whereas when HAP particle size reaches to nanometer level, the HAP particles are liabe to agglomerate, so this method can make the dispersion activity of HAP dispersant decrease on the contrary. Therefore, in order to obtain superfine HAP dispersants with high activity, the surfaces of these HAP particles must be modified so as to decrease agglomeration. As a result, this method may...